1. Field of the Invention
The invention is directed to an apparatus for smoothing an inner toothing and/or an outer toothing according and to a method for producing an inner toothing and/or outer toothing.
2. Detailed Description of the Prior Art
It is known that the inner teeth of ring gears are initially machined by broaching and, in the case of helical teeth, by helical broaching. As a result of the broaching process, pointed ridge-shaped structures occur on the surface of the tooth flanks leading to unwanted surface roughness on the tooth flanks. Excessive surface roughness is one of the causes of micropitting, or pitting, which develops on the tooth flanks during operation of the gears. It is also known that the surface roughness produced by chip-removing machining can be reduced by smoothing. In this smoothing process, the profile peaks of the rough surface are smoothed by deformation. This can improve the surface quality of the tooth flanks and eliminate a cause of micropitting.
A device for smoothing an inner toothing of a ring gear is known from DE 199 63 477 A1. The device comprises three machining units which are offset by 90° with respect to one another and which have a smoothing gear in each instance. The ring gear is clamped in a holder and swiveled by 90-degree increments on a revolving table so as to run through the three machining stations. The smoothing gears are meshed to the inner toothing of the ring gear on each of the three machining stations and accordingly effect a smoothing of the inner toothing successively, i.e., in three temporally and spatially consecutive steps. The smoothing gear is advanced radially from the inner side to the outer side in each instance, for which purpose a pressing force is applied by disk springs. The smoothing gears are driven in each instance by a motor and roll along the inner toothing and are simultaneously oscillated in axial direction. The three smoothing gears of the different machining stations are directed to different portions of the tooth flanks.
It is also known, e.g., from DE 10 2007 039 959 A1, to smooth-roll an outer toothing of a gear through two diametrically disposed round rolling tools.